The isolated hepatocytepreparation provides a useful model system for investigation of the factors that control hepatic lipid and lipoprotein production and catabolism. The simplified enzyme perfusion method that I devised for preparation of dispersed rat liver cells has been successfully adapted to the atherosclerosis-prone squirrel monkey (Saimiri sciureus) and the White Carneau pigeon and to the atherosclerosis-resistant Show Racer pigeon. Hepatocytes from these animals rapidly incorporate precursors into lipids, proteins, and plasma lipoproteins. The proposed research is designed to gain information on the effects of cyclic AMP, its derivatives, hormones, and hypolipidemic agents on the regulation of hepatic lipid and lipoprotein production and degradation and on the mechanism of these effects. Studies will be done with freshly prepared and with cultured hepatocytes to elucidate both rapid and inductive effects. Comparative studies will be performed with atherosclerosis-prone and atherosclerosis-resistant pigeons to identify derangements in metabolic control of lipoprotein metabolism that may render one strain more susceptible to atherosclerosis than the other.